Transcript Chapter 14
The Theory of Evolution by Natural Selection Charles Darwin Western Historical Context Aristotle (384-322 B.C.) – Greek philosopher Species are permanent, perfect, immutable Dominant world view for > 2000 yr See timeline Fig. 22.2 Western Historical Context A.D. – Natural Theology (Creationism) Species are permanent, perfect, immutable See timeline Fig. 22.2 Western Historical Context Carolus Linnaeus (1707-1778) Swedish physician & botanist whose passion was taxonomy Developed a hierarchical classification scheme & binomial nomenclature See timeline Fig. 22.2 Western Historical Context Carolus Linnaeus (1707-1778) Canis = genus lupus = specific epithet that refers to one species in the genus Canis The binomial is always italicized or underlined, the genus name is always capitalized, and the specific epithet is always lower case See Fig. 25.8 “King Philip Came Over For Gumbo Sunday” Western Historical Context Georges Cuvier (1769-1832) French anatomist who largely developed paleontology, the study of fossils See timeline Fig. 22.2 Western Historical Context Georges Cuvier (1769-1832) Deeper strata contain older taxa See timeline Fig. 22.2 Western Historical Context Georges Cuvier (1769-1832) Preferred hypothesis for profound geologic change = catastrophism See timeline Fig. 22.2 Western Historical Context James Hutton (1726-1797) Scottish geologist who offered an alternative to catastrophism Preferred hypothesis for profound geologic change = gradualism See timeline Fig. 22.2 Western Historical Context Charles Lyell (1797-1875) Scottish geologist who incorporated Hutton’s gradualism into the theory of uniformitarianism See timeline Fig. 22.2 Western Historical Context Charles Lyell (1797-1875) Uniformitarianism – geological processes & rates today are those that also operated in antiquity See timeline Fig. 22.2 Western Historical Context Charles Lyell (1797-1875) Uniformitarianism – suggested that the Earth is > 6000 yr old See timeline Fig. 22.2 Western Historical Context Jean Baptiste Lamarck (1744-1829) Invertebrate Curator of the Natural History Museum in Paris One of the 18th & 19th centuries’ biologists who hypothesized that traits of species are not immutable, i.e., they can evolve See timeline Fig. 22.2 Western Historical Context Jean Baptiste Lamarck (1744-1829) Hypothesized mechanism of evolution: Use & disuse alters traits; inheritance of acquired characters results in adaptations to environmental conditions See timeline Fig. 22.2 Western Historical Context Thomas Malthus (1766-1834) English demographer Hypothesis: Plants and animals are capable of producing far more offspring than resources can support; the “struggle for existence” (e.g., famine, war) is an inescapable consequence See timeline Fig. 22.2 Western Historical Context Within this context, Charles Darwin (18091882) served as Ship’s Naturalist on the HMS Beagle’s circumnavigation of the globe (1831-1836) England EUROPE NORTH AMERICA ATLANTIC OCEAN PACIFIC OCEAN Galápagos Islands HMS Beagle in port SOUTH AMERICA AUSTRALIA Andes Darwin in 1840, after his return AFRICA Cape of Good Hope Cape Horn Tierra del Fuego Tasmania New Zealand Galapagos Islands, Ecuador Galapagos Islands, Ecuador Galapagos Islands, Ecuador Galapagos Islands, Ecuador Darwin was a good observer of both wild and domesticated organisms (e.g., birds) Darwin was a good observer of both wild and domesticated organisms (e.g., birds) Western Historical Context Charles Darwin (1809-1882) English gentleman who conceived of natural selection as the principal mechanism of adaptive evolution See timeline Fig. 22.2 Western Historical Context Alfred Russel Wallace (1823-1913) English biologist who also (independently) conceived of natural selection as the principal mechanism of adaptive evolution See timeline Fig. 22.2 Western Historical Context Lyell presented the independently derived hypothesis to the Linnaean Society of London on July 1, 1858 Western Historical Context Charles Darwin (1809-1882) The Origin of Species (1859) The Origin of Species Final paragraph: “It is interesting to contemplate an entangled bank, clothed with many plants of many kinds, with birds singing on the bushes, with various insects flitting about, and with worms crawling through the damp earth, and to reflect that these elaborately constructed forms, so different from each other, and dependent on each other in so complex a manner, have all been produced by laws acting around us… There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed laws of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.” Darwinian Theory of Evolution Descent with modification Descent implies common ancestry Modification to better suite the environment = adaptation Natural selection is the principal process that drives adaptive evolution See Fig. 22.7 Darwinian Theory of Evolution Organisms have enormous potential for population increase, but the potential is rarely reached Generalized sigmoidal population growth curve Potential for rapid population growth when resources are not limiting Resource availability generally limits population size Competition for resources (“struggle for existence”) Phenotypic variability (morphology, physiology, behavior, etc.) Natural Selection: Survival and reproduction of the “fittest” individuals Some variability results from heritable differences Adaptive evolution: A change in the phenotypic constitution of a population owing to selection on heritable variation among phenotypes Lamarckism Use Inheritance of acquired characteristics Darwinism Natural selection Generation 1 Genetic inheritance from selected population Generation 2 Evidence for the Theory of Evolution by Natural Selection Darwin used artificial selection to illustrate the modifying potential of selection Evidence for the Theory of Evolution by Natural Selection Darwin used artificial selection to illustrate the modifying potential of selection Evidence for the Theory of Evolution by Natural Selection Darwin used artificial selection to illustrate the modifying potential of selection Evidence for the Theory of Evolution by Natural Selection Rapid changes in populations under strong selection E.g., pesticide resistance Evidence for the Theory of Evolution by Natural Selection Homologous traits (a.k.a. characters, attributes) = traits in different species that arose from the same ancestral trait (may or may not have similar function) See Fig. 22.14 Human Cat Whale Bat Evidence for the Theory of Evolution by Natural Selection Even when homologies are not obvious in adults, they may be quite apparent in embryonic stages Lemur Pig Human Which one is the human? Evidence for the Theory of Evolution by Natural Selection Analogous traits = traits in different species that have similar function, but arose from different ancestral traits To distinguish homologous vs. analogous traits, the relatedness of the organisms doesn’t matter as much as the evolutionary history of the traits themselves Evidence for the Theory of Evolution by Natural Selection Analogous traits = traits in different species that have similar function, but arose from different ancestral traits Evidence for the Theory of Evolution by Natural Selection Vestigial organs = remnants of organs that had important functions in ancestors These examples happen to be homologous leg and foot bones Evidence for the Theory of Evolution by Natural Selection Vestigial organs = remnants of organs that had important functions in ancestors Evidence for the Theory of Evolution by Natural Selection Biochemical homologies Common use of DNA, RNA, amino acids, ribosomes, genetic code, ATP, electron carriers, electron transport system, etc.